The present invention is related to an apparatus for removing a welding bulge, and in particular, to an apparatus for removing a welding bulge from resistance welded pipes while laying pipelines.
Variously constructed and modified apparatus for removing a welding bulge, intended for operation in specific conditions, are well known in the art.
The invention is directed to the apparatus designed for field operation while laying pipelines for the longdistance transportation of petroleum and gas. More specifically, the present invention has to do with an apparatus designed for removing a welding bulge from resistance welded pipes under the aforesaid conditions.
Apparatus thus far proposed as exemplified in USSR inventor's Certificates Nos. 507373, 468729, 468730, generally comprise impact or cutting tools, motion and static parts, and mechanisms for driving the tools.
Such apparatus, particularly those intended for large-diameter (over 1,000 mm) pipes, are of large dimensions and of considerable weight and therefore present problems in service and are greatly time-consuming for setup under field conditions in pipeline construction. As a consequence, their performance has proved to be lower than that of the electric resistance welding machines, which machines together with the apparatus in question form part of a single production complex.
Known in the prior art is an apparatus for removing a welding bulge from resistance welded pipes as disclosed in USSR Inventor's Certificate No. 589090, said apparatus comprising a ring-shaped carrier adapted to be placed at the bulge zone in spaced circumferential relationship to the welded pipes and being provided with centering rollers, as well as milling cutter units pivotally associated with the carrier for radial movement to and from the weld bulge and said milling cutter units being provided with former rollers.
The centering rollers are motor-operated, enabling the carrier to be turned about the pipes at the weld bulge zone.
In operation, the motor-operated centering rollers by rolling over the pipes impart rotary motion to the carrier. As this takes place, the milling cutter units will approach the weld bulge and the carrier will provide the feed of this tool.
Though simple in construction this apparatus still suffers from a number of disadvantages.
Inasmuch as the motor-operated centering rollers of the known apparatus are supported on the welded pipes, the reliability of the drive for feeding the milling cutter units is completely dependent on the engagement of the motor-operated rollers with the surface of the pipe, providing the drive power is sufficient to defeat resistance of the weld material to the milling cutter units.
The reliability of the roller-pipe engagement is in turn dependent on the surface condition of the pipes and the rollers, since under field conditions there may be ice formation, oil film, and other friction-affecting deposition formations.
This brings about vibration in the tools of the milling cutter units and a drop in the speed of feeding thereof, which in turn impair performance of the prior art apparatus. The problem of performance appears to be even more acute by appreciation of the fact that in view of the above the welding bulge has to be removed in more than one pass.
The present invention contemplates the provision of an apparatus for removing a welding bulge from end-to-end resistance welded pipes which is simple in construction, and offers higher reliability and performance characteristics.